| 摘要 |
PURPOSE:To enable the current level of a beam to be controlled continuously even after an electron-beam producing part is made vacuum by enabling the distance between the anode and the cathode to be varied without breaking the vacuum of the beam producing part. CONSTITUTION:A cathode 2 and a grid 3 are fixed and supported in a vacuum case 1. An anode 4 facing these members can be moved vertically by means of a rack 5 and pinion 6. The pinion 6 can be rotated from outside the case 1 through a shaft penetrating the wall of the case 1. An anode-supporting shaft 7 is fixed to the case 1. The anode 4 is connected inside the supporting shaft 7 in such a manner as to be vertically slidable. Owing to such constitution as above, the current level of a beam can be controlled continuously even after an electron-beam producing part is made vacuum. |
